sudo nano /etc/wpa_supplicant/wpa_supplicant.conf

sudo nano /etc/dhcpcd.conf

sudo apt purge libpam-chksshpwd

sudo raspi-config
Advanced Options
SSH
Serial

System>Hostname>rpi3

System>Display>Set Resolution

System>Interfaces> SSH>Enable

System>Interfaces> VNC>Enable

sudo adduser XYZ

sudo adduser XYZ sudo

sudo nano /etc/lightdm/lightdm.conf

 autologin-user=XYZ

reboot and login with user XYZ

sudo userdel -r -f pi

sudo rm -rf /home/pi/

if you are under a proxy network you need to configure proxy settings so that your pi can communicate with Internet
for that you need to configure this file.

sudo nano /etc/environment

//////////////////////////////////////////////////////////////////////////////////////////////

export http_proxy="http://username:password@proxyipaddress:proxyport"
export https_proxy="http://username:password@proxyipaddress:proxyport"
export no_proxy="localhost, 127.0.0.1"

sudo visudo
Defaults env_keep+="http_proxy https_proxy no_proxy"

sudo apt update
sudo apt upgrade

sudo nano /boot/config.txt

max_usb_current=1
hdmi_group=2
hdmi_mode=87
hdmi_cvt 1024 600 60 6 0 0 0
hdmi_drive=1

Disable Screen Sleep

1. sudo apt-get install xscreensaver
2. Once installed, go to Rpi's desktop "Menu" (left top corner)
3. Go to preference --> screensaver.
4. You will see a screen saver main menu. In the mode drop-down menu, select "disable screensaver" then close the window.
5. Reboot the Raspberry PI.